Tinsley Viaduct

Tinsley Viaduct is a two-tier road bridge in Sheffield, England; it was the first of its kind in the United Kingdom. It carries the M1 and the A631 3,389 feet (1,033 m) over the Don Valley, from Tinsley to Wincobank, also crossing the Sheffield Canal, the Midland Main Line and the former South Yorkshire Railway line from Tinsley Junction to Rotherham Central. The Supertram route to Meadowhall runs below part of the viaduct on the trackbed of the South Yorkshire Railway line to Barnsley.

Tinsley Viaduct
Tinsley Viaduct as seen from Meadowhall, with the two cooling towers of the former Blackburn Meadows power station before their demolition in 2008.
Coordinates53°25′03″N 1°24′21″W
Carries
Crosses
LocaleTinsley/Wincobank
Maintained byHighways England
Characteristics
Designtwin deck box girder bridge[1]
Total length1,033 m (3,389 ft)
Width6 lanes
Height20 m (66 ft) (to upper level)
Longest span50 m (160 ft) (20 spans)
Clearance above10 m (33 ft) (on the A631)
Clearance below10 m (33 ft)[2]
History
Construction startSpring 1965[3]
Construction end1968
Opened25 March 1968 (lower deck)[3]
19 October 1968 (upper deck)[4]
Statistics
Daily traffic100,000 vehicles/day[5]
Location

History
Tinsley Viaduct lower deck.

The lower deck of the viaduct was opened in March 1968[6] and the upper deck, carrying the M1, on 19 October 1968.[4] The build cost was £6 million. The structure is unusual in that it is built as steel box girders, at a time when most long span bridges were being built of post-tensioned concrete deck design. This use of steel allowed a significant cost saving over alternative methods, but became controversial after three serious disasters, when new bridges collapsed in 1970 (West Gate Bridge and Cleddau Bridge) and 1971 (South Bridge (Koblenz)). Fifty-one people were killed in these failures, leading in the UK to the formation of the Merrison Committee.[7] The report of the Merrison committee resulted in the temporary closure of two of the carriageways on the lower deck and two on the upper deck, the installation of extra steel strengthening bands around the bridge's support columns and other works which were completed in 1983. A further programme of strengthening was completed in 2006. The recent work to strengthen the bridge was a very complex operation, with a lot of the work happening inside the box beam spine. The works took over 3 years and cost £82 million (14 times the original bridge building cost). The strengthening project won the British construction industry's Major Project Award in 2005.

Although originally designed to carry a dual 3-lane motorway on the top deck, during and subsequent to the strengthening work the M1 was reduced to 2 lanes following an EU directive on load bearing capacity to allow for the introduction of 40-tonne trucks in the UK. This arrangement allowed the third lane in each direction to join from Junction 34 to make the busy junction safer.[8] Since the opening of the M1 junction 32 to 35a smart motorway scheme in January 2017, the viaduct once again carries 3 lanes of traffic plus hard shoulders in each direction.[9]

The viaduct is balanced on rollers to allow for thermal expansion and contraction, and the route weaves slightly in order to make its way past obstacles. The viaduct, due to its construction, is very flexible. Movement may be felt on the lower deck as the traffic passes overhead. The Meadowhall Shopping Centre lies in the valley to the west; to the east is the Blackburn Meadows sewage works and new biomass power station.

Tinsley cooling towers
Main article: Blackburn Meadows Power Station
Demolition of Tinsley cooling towers on 24 August 2008.

The viaduct is one of Sheffield's most prominent landmarks, and was once made all the more so by the adjacent pair of cooling towers that were left standing for safety reasons after the demolition of the Blackburn Meadows Power Station. The cooling towers were a major point of contention over the years and were once saved from destruction only after being chosen as a nesting site by a rare bird. More recently, plans were made to turn them into a piece of public art.[10] Other plans for the towers included concert halls, skate parks and a theme park.

Their iconic status, and the possibly prohibitive costs of demolishing the towers safely, until recently looked to have cemented their status in Sheffield's future as much as they were a part of its history, until the owner of the towers (and the now-demolished power station), E.ON UK, stated its intention to demolish them once the strengthening of the viaduct made it feasible.[11]

The 250 feet (76 m) towers were demolished at 03:00 BST on 24 August 2008, though a significant portion of the north tower remained standing for a short while. The demolition attracted widespread attention. A viewing platform was set up so the public could watch the demolition.[12] Part of the site has been converted for use as a biomass power station by the owners E.ON UK.[13][14]

The Tinsley Viaduct was "ground zero" for a fictional Soviet Union nuclear strike on Sheffield depicted in Threads (1984), a depiction of what might have happened had NATO and the Soviet Union entered conflict over hypothetical instability in Iran that escalated into full nuclear war. In the ensuing nuclear exchange, a one-megaton nuclear missile detonates above the Tinsley Viaduct, devastating most of surrounding Sheffield.

See also

References
  1. "Tinsley Viaduct". Highways Agency. Retrieved 17 April 2007.
  2. "Safespan's Latest News". Safespan Inc. Retrieved 28 December 2007.
  3. "M1 Aston-Sheffield-Leeds". The Motorway Archive Trust. Archived from the original on 27 September 2007. Retrieved 19 April 2007.
  4. "Superway". The Guardian. 21 October 1968. p. 12. Retrieved 27 January 2019. – via newspapers.com (subscription required)
  5. "Tinsley viaduct strengthening project, Sheffield". Prime Minister's Award. Archived from the original on 5 December 2008. Retrieved 17 April 2007.
  6. Leleux, Sydney A. (February 1969). "Tinsley Viaduct, Sheffield". Retrieved 16 November 2006.
  7. Department of the Environment (Merrison Committee of Inquiry) (1973). Inquiry into the Basis of Design and Method of Erection of Steel Box Girder Bridges. London: HMSO.
  8. "£82 Million M1 Tinsley Viaduct strengthening work nears completion". Highways Agency. 10 October 2005. Retrieved 16 November 2006.
  9. "Transforming the M1 in Yorkshire and the East Midlands". gov.uk. 12 September 2014. Retrieved 12 September 2017.
  10. "Turning towers into art". BBC News. BBC. 8 July 2006. Retrieved 28 August 2006.
  11. "August demolition date set for Tinsley cooling towers". E.ON UK. 12 August 2008. Retrieved 12 August 2008.
  12. "Blast demolishes landmark towers". BBC News. BBC. 24 August 2008. Retrieved 24 August 2008.
  13. "E.ON UK Blackburn Meadows Green powerstation". E.ON. Retrieved 24 August 2008.
  14. "E.ON's Blackburn Meadows biomass plant generates electricity | Bioenergy Insight Magazine". bioenergy-news.com. 30 June 2014. Retrieved 12 September 2017.
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